Mueller PMC 40/50 - Thermal Expansion Valve (TEV) Superheat Adjustment

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Mueller Bakery Chiller, Models PMC 40/50 and PMC 70/120 Effective February 23, 1999

Installation and Operation Manual, Part No. 9842311 Revised October 17, 2019

7.5 THERMAL EXPANSION VALVE (TEV) SUPERHEAT ADJUSTMENT

Take the following readings with the water storage tank full of water at a temperature below 40°F.

1. Take an accurate suction pressure at the evaporator outlet.

IMPORTANT: The suction pressure must be taken at the evaporator outlet, rather than the suction

service valve, due to unknown pressure drop in the refrigerant line between the evaporator and the

compressor (refer to Figure 8). The technician should also make certain the system is charged with

refrigerant, as described in Section 2.0.

2. Take an actual suction line temperature near the TEV sensing bulb using an accurate electronic thermometer.

3. Utilizing the pressure temperature chart for the appropriate refrigerant, convert the suction pressure reading

from Step 1 to saturation temperature.

4. The superheat value is found by subtracting the saturation temperature determined in step 3 from the actual

suction line temperature taken in step 2.

5. If the superheat is not in the range of 8 to 10°F, at conditions described above, adjust the TEV.

6. If the superheat is below 8°F, turn the TEV’s adjustment stem clockwise

⁄8 to

⁄4 of a turn. Allow the system to

operate for five minutes before repeating test.

7. If the superheat is above 10°F, turn the TEV’s adjustment stem counterclockwise

⁄8 to

⁄4 of a turn. Allow the

system to operate for five minutes before repeating test.

8. Any time adjustment is made to the TEV, the refrigerant charge should be checked. If refrigerant must be

added, care must be taken to meter the liquid refrigerant into the system slowly to avoid introducing liquid into

the compressor.

IMPORTANT: Damage to the compressor may occur if the liquid refrigerant reaches the compressor.

9. Check the superheat setting and make final adjustments at a product temperature near the setpoint for the

best performance.